The Local IP Access (LIPA) of the conventional Residential Network is supported only in the situation where a Local Gateway (L-GW) is co-located with Home (evolved) Node B (hereinafter, H(e)NB).
FIG. 1 is a diagram illustrating a structure of an LIPA-enabled network 110 which does not support Session Continuity. Referring to FIG. 1, the local network includes an H(e)NB 106 and L-GWs 104 responsible for gateway function which constitute one entity 102 logically. The H(e)NB 106 and L-GWs 104 communicate through internal interfaces. The UE 100 uses the H(e)NB to communicate with another IP device 108 present in the local network. At this time, the data packets of the user are transmitted to the other IP device 108 through the L-GW 104 in the location network. The local network based on the co-located L-GW 104 is advantageous in simple network structure. However, as described above, such a local network has a drawback of not supporting Session Continuity.
FIG. 2 is a diagram illustrating a configuration of LIPA Mobility and SIPTO at the Local Network (LIMONET). In order to overcome the drawback of the network as shown in FIG. 1, LIMONET has been introduced as a concept in which the H(e)NB and L-GW are logically separated, i.e. in the form of stand-alone local network.
As shown in FIG. 2, the local network 210 may include a stand-along L-GW 204 in the LIMONET environment. At this time, a plurality of H(e)NBs 206 and 216 and L-GWs 204 and 212 may be installed and operate in one local network 210. Since the L-GW 204 and H(e)NB 206 are logically separated, the L-GW 204 has to maintain a connection with the H(e)NB 206 for providing the UE 200 or other IP devices 202 with the connection service. Meanwhile, the local network 210 may include an entity 214 co-located with the H(e)NB and L-GW as shown in FIG. 2.
FIG. 3 is a diagram illustrating a network structure for supporting stand-along L-GW. As shown in FIG. 3, the L-GW and the H(e)NB are connected to each other. The connection interface between the L-GW and H(e)NB is referred to as Sxx interface 300.
Returning to FIG. 2, the structure in which the H(e)NB and L-GW are separated so as to support mobility (hereinafter, referred to as Rel-11 HeNB) and another structure in which the H(e)NB and L-GW are co-located so as not to support mobility (hereinafter, referred to as PRE Rel-11 HeNB) may coexist.
FIG. 4 is a diagram illustrating UE mobility in the network where the Rel-11 HeNB and PRE Rel-11 HeNB coexist. In FIG. 4, it is assumed that the UE 400 has established an LIPA PDN connection to the stand-alone L-GW 404 through Rel-11 H(e)NB. If another H(e)NB 406 nearby the H(e)NB 402 is the Rel-11 H(e)NB, the UE may move between the H(e)NBs 402 and 406 while maintaining the LIPA PDN connection. However, if the nearby H(e)NB is the PRE Rel-11 H(e)NB 408, the H(e)NB cannot establish a connection with the stand-alone L-GW 404. Therefore, the system cannot support mobility of the UE 400 between the two H(e)NBs 406 and 408 while maintaining the LIPA PDN connection.